diff --git a/Gemfile b/Gemfile
index c79ab25b..0f92d58a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,6 +4,6 @@ gemspec
 
 group :development, :test do
   # ref: http://docs.rubocop.org/en/latest/installation/
-  gem 'rubocop', '~> 1.55.0', require: false
+  gem 'rubocop', '~> 1.56.0', require: false
   gem 'yard', '~> 0.9.20'
 end